Friction of flat and micropatterned interfaces with nanoscale roughness

Saad Bin Jaber, Alex Hamilton, Yang Xu* (Corresponding Author), Mehmet E. Kartal, Nikolaj Gadegaard, Daniel M Mulvihill* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

The dry friction of surfaces with nanoscale roughness and the possibility of using micropatterning to tailor friction by manipulating contact area is investigated. Square wave patterns produced on samples from silicon wafers (and their unstructured equivalent) were slid against unstructured silicon counter surfaces. The width of the square wave features was adjusted to vary the apparent feature contact area. The existence of nanoscale roughness was sufficient to ensure Amontons' first law (F = mu P) on both structured & unstructured samples. Somewhat counterintuitively, friction was independent of the apparent feature contact area making it difficult to tailor friction via the feature contact area. This occurred because, even though the apparent feature contact area was adjusted, the surface roughness and nominal flatness at the contact interface was preserved ensuring that the real contact area and thereby the friction, were likewise preserved. This is an interesting special case, but not universally applicable: friction can indeed be adjusted by structuring provided the intervention leads to a change in real contact area (or interlocking)- and this depends on the specific surface geometry and topography.

Original languageEnglish
Article number106563
Number of pages8
JournalTribology International
Volume153
Early online date25 Jul 2020
DOIs
Publication statusPublished - 31 Jan 2021

Keywords

  • Dry friction
  • Surface structure
  • Surface roughness
  • CRYSTALLIZATION
  • CONTACT
  • MECHANICS
  • AREA
  • ALIGNMENT
  • STEEL SURFACES

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